Three dimensional printed hardfacing on a downhole tool

ABSTRACT

The present disclosure provides downhole tools, methods for three dimensional printing hardfacing on such downhole tools, and systems for implementing such methods.

PRIORITY CLAIM

The present application is a U.S. National Stage Application ofInternational Application No. PCT/US2017/056961 filed Oct. 17, 2017,which designates the United States.

TECHNICAL FIELD

The present disclosure relates generally to hardfacing on downholetools.

BACKGROUND

Various types of downhole tools are used to form wellbores in downholeformations. It is common practice to form a downhole tool with aparticular configuration and to subsequently treat part of the downholetool to provide abrasion, erosion and/or wear resistance. One type oftreatment includes applying a layer of hard abrasion, erosion and/orwear resistant material, often referred to as hardfacing, to a surfaceof the downhole tool. Hardfacing is frequently applied to a downholetool using conventional welding techniques to extend the service life ofthe tool.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure and itsfeatures and advantages thereof, reference is now made to the followingdescription, taken in conjunction with the accompanying drawings anddetailed description, wherein like reference numerals represent likeparts, in which:

FIG. 1 is an elevation view of selected elements of a drilling system inwhich a downhole tool with hardfacing on at least one surface may beused;

FIG. 2A is a schematic drawing in elevation showing selected elements ofa rotary cone drill bit with hardfacing;

FIG. 2B is a schematic drawing in elevation showing selected elements ofa fixed cutter drill bit with hardfacing;

FIG. 3 is a drawing partially in section and partially in elevation withportions broken away showing selected elements of a roller cone assemblyand a support arm of the drill bit of FIG. 2A with hardfacing;

FIG. 4 is a block diagram of a hardfacing system for three dimensionalprinting (3D) hardfacing;

FIG. 5 is a block diagram of the hardfacing system of FIG. 4 as used inthree dimensional printing hardfacing on the roller cone assembly ofFIG. 3;

FIGS. 6A and 6B are photographs of damaged tungsten carbide particles inhardfacing following exposure to excessive heat; and

FIG. 7 is a flow chart of a method for 3D printing hardfacing.

DETAILED DESCRIPTION

The present disclosure relates to a hardfacing system and methods ofapplying hardfacing to a downhole tool using the hardfacing system,including a hardfacing system for 3D printing hardfacing and methods of3D printing hardfacing. The system and method may allow controlled,automated hardfacing of a downhole tool. The system and method may alsodecrease or avoid thermal damage of the hardfacing.

The disclosed systems and methods and their advantages may be bestunderstood by referring to FIGS. 1-7 of the drawings, in which likenumerals refer to like parts.

Turning now to the drawings, FIG. 1 is an elevation view of a drillingsystem in which a downhole tool containing hardfacing on surfaces of thedownhole tool may be used. Drilling system 100 includes a well surfaceor well site 106. Various types of drilling equipment such as a rotarytable, drilling fluid pumps and drilling fluid tanks (not expresslyshown) may be located at well surface or well site 106. For example,well site 106 may include drilling rig 102 that may have variouscharacteristics and features associated with a land drilling rig.However, downhole tools incorporating teachings of the presentdisclosure may be satisfactorily used with drilling equipment located onoffshore platforms, drill ships, semi-submersibles, and/or drillingbarges (not expressly shown).

When configured for use with a rotary drill bit, drilling system 100includes drill string 104 associated with drill bit 108, typicallythrough a bottom hole assembly (BHA). The drilling system may be used toform a wide variety of wellbores or bore holes such as generallyvertical wellbore 110 or a directional wellbore, such as generallyhorizontal wellbore 110, or any combination thereof. Drilling system 100may be configured in alternative ways for other downhole tools.

In the present disclosure, drill bit 108 or another downhole tool indrilling system 100 includes hardfacing on the bit. The hardfacing mayhave been applied on one or more surfaces of the downhole tool by ahardfacing system using three dimensional (3D) printing hardfacing. Thehardfacing may optimize drill bit 108 or another downhole tool for theconditions experienced during the drilling operation to increase thelife span of drill bit 108 or another downhole tool. Although drill bit108 is depicted as a fixed-cutter drill bit, any drill bit, such as arotary drill bit, having a bit head with hardfacing on one or moresurfaces of the drill bit, such as a rotary drill bit, may be used indrilling system 100. Other components of drilling system 102, such asreamers, core bits, under reamers, near bit reamers, hole openers,stabilizers, centralizers, and shock absorber assemblies may havehardfacing on at least surface in addition to or as an alternative tohardfacing on drill bit 108.

Hardfacing may be on at least one surface of a downhole tool used toform a wellbore, particularly if such surface may benefit fromprotection from abrasion, erosion and/or wear. Such surface of thedownhole tool may be formed from various metal alloys and/or cermetshaving particular metallurgical characteristics such as machinability,toughness, and heat treatability and/or corrosion resistance. Forexample, a surface may be formed from various steel alloys used indownhole tools.

FIGS. 2A and 2B are elevation views showing selected elements of arotary cone drill bit 120 and a fixed cutter drill bit 160, respectivelywith hardfacing 126. Rotary cone drill bit 120 or fixed cutter drill bit160 may be used as rotary drill bit 108 of FIG. 1.

Hardfacing 126 disposed on rotary cone drill bit 120 is shown in FIGS.2A, 3 and 5 and hardfacing 126 disposed on fixed cutter drill bit 160 isshown in FIG. 2B. In FIGS. 2A, 2B, 3 and 5, hardfacing 126 isillustrated as disposed on multiple surfaces. Hardfacing 126 may includeat least one hard material particle and at least one matrix material.

Hard material particles in hardfacing 126 may be in the form of powders,pellets, or other small discrete objects. Hardfacing 126 may be in awide range of mesh sizes, such as between 12 U.S. mesh and 400 U.S.mesh. The ability to use a wide range of mesh sizes may substantiallyreduce costs of 3D printing hardfacing 126 on downhole tools. It mayalso reduce costs associated with the hardfacing system components.

The matrix material component of hardfacing 126 has a meltingtemperature below the melting temperature or melting temperatures of theparticles and and/or below the temperature at which the particle orparticles begin to experience thermal damage or degradation. The matrixmaterial component is melted by hardfacing systems as described hereinduring methods of applying hardfacing as described herein.

Hardfacing 126, particularly the matrix material component of hardfacing126, may include any of a variety of hard materials such as, but notlimited to, at least one material selected from the group consisting ofa metal, a metal alloy, a ceramic alloy, a cermet, and any combinationsand/or sub-combinations thereof. Hardfacing 126, particularly the matrixmaterial component of hardfacing 126, may include any of a variety ofhard materials such as, but not limited to, at least one materialselected from the group consisting of an iron alloy, an iron, manganese,and silicon alloy, copper, a copper alloy, nickel, a nickel alloy,cobalt, a cobalt alloy, and any combinations and/or sub-combinationsthereof.

Hardfacing 126, particularly the hard material particles of hardfacing126, may include a metal boride, metal carbide, a metal nitride, a metalsilicide and any combinations and/or sub-combinations thereof.Hardfacing 126, particularly the hard material particles of hardfacing126, may include at least one material selected from the groupconsisting of tungsten, tungsten boride tungsten carbide, tungstennitride, tungsten oxide, tungsten silicide, copper, copper boride,copper carbide, copper oxide, copper nitride, copper silicide, niobium,niobium boride niobium carbide, niobium nitride, niobium oxide, niobiumsilicide, vanadium, vanadium boride vanadium carbide, vanadium nitride,vanadium oxide, vanadium silicide, molybdenum, molybdenum boridemolybdenum carbide, molybdenum oxide, molybdenum nitride, molybdenumsilicide, titanium, titanium boride titanium carbide, titanium oxide,titanium nitride, titanium silicide, tantalum, tantalum boride tantalumcarbide, tantalum oxide, tantalum nitride, tantalum silicide, zirconium,zirconium boride, zirconium carbide, zirconium oxide, zirconium nitride,zirconium silicide, chromium, chromium boride chromium carbide, chromiumoxide, chromium nitride, chromium silicide, yttrium, yttrium borideyttrium carbide, yttrium oxide, yttrium nitride, yttrium silicide,boron, boron carbide, boron oxide, boron nitride, boron silicide,silicon, silicon boride, silicon carbide, silicon oxide, siliconnitride, and any combinations and/or sub-combinations thereof.

The bit body of roller cone drill bit 120 may be manufactured from ametal, such as a steel alloy, particularly a strong, ductile steel alloyhaving high strength and toughness, and reasonable machinability. Suchsteel alloys generally do not provide good, long term cutting surfacesand cutting faces because such steel alloys are often rapidly worn awayduring direct contact with adjacent portions of a downhole formation. Toincrease downhole service life of roller cone drill bit 120, hardfacing126 may be applied on at least one of a shirttail surface, a backfacesurface, a milled tooth, an insert and/or another surface that mayfrequently contact the formation or debris. Hardfacing 126 may also beapplied on any other portions of drill bit 120 which may be subjected tointense erosion, wear and/or abrasion during drilling. For some downholetools, at least 50%, at least 80%, or at least 95% of the total exteriorsurface area of roller cone 122 may be covered with hardfacing 126.

Arms 134 may extend from bit body 124 opposite from threaded connection130. Two substantially identical arms 134 are shown in FIG. 2A. Othernumbers of arms may be present. The lower end portion of each arm 134may be provided with a bearing pin or spindle to rotatably supportgenerally conical roller cone assembly 122. FIG. 3 shows roller coneassembly 122, which has been rotatably mounted on spindle 136 extendingfrom the lower portion of each support arm 134.

Drill bit 120 includes bit body 124 connectable by pin or threadedconnection 130 to the lower end of a drill string (not expressly shown).Bit body 124 may include a passage (not shown) that provides downwardcommunication for drilling mud or other fluids passing downwardlythrough an associated drill string.

Drilling mud or other fluids may exit through one or more nozzles 132and be directed to the bottom of an associated wellbore. They then maypass upwardly in an annulus formed between the wall of the wellbore andthe outside diameter of the drill string. The drilling mud or otherfluids may be used to remove formation cuttings and other downholedebris from the bottom of the wellbore. The flow of drilling mud,formation cuttings and other downhole debris may erode various surfacesand substrates on bit body 124, support arms 134 and/or cone assemblies122. Such surfaces may be protected by hardfacing 126.

As shown in FIGS. 2A and 3, hardfacing 126 may be on exterior surfacesof support arms 134 adjacent to the respective roller cone assemblies122. This portion of each support arm 134 may also be referred to as theshirttail surface. Hardfacing 126 may also be on backface surface orgauge ring surface 138 of each roller cone assembly 122. As shown inFIG. 3, the exterior surface area of roller cone assembly 122 may becompletely covered with hardfacing 126 except for inserts 128.

As shown in FIG. 2B, the bit body of fixed cutter drill bit 160 may bemanufactured from a metal, such as a steel alloy, particularly a strong,ductile steel alloy having high strength and toughness, and reasonablemachinability. To increase downhole service life of fixed cutter drillbit 160, hardfacing 126 may be applied on various portions of blades 164and/or exterior portions of bit body 162. Hardfacing 126 may also beapplied in junk slots 170 formed between adjacent blades 164, and atleast one of a shirttail surface, a backface surface, a milled tooth, aninsert and/or another surface that may frequently contact the formationor debris. Hardfacing 126 may also be applied on any other portions ofdrill bit 160 which may be subjected to intense erosion, wear and/orabrasion during drilling.

Drill bit 160 includes bit body 162 connectable by pin or threadedconnection to the lower end of a drill string (not expressly shown) atproximate end 172 of bit body 162. Bit body 162 may include a passage(not shown) that provides downward communication for drilling mud orother fluids passing downwardly through an associated drill string. Oneor more nozzles 132 may be provided in bit body 162 to direct the flowof drilling mud or other fluids therefrom. Hardfacing 126 may be appliedon or near nozzles 132.

Cutting elements 178 disposed on associated blades 164 may contactadjacent portions of a downhole formation (not expressly shown). Theinside diameter of an associated wellbore may be generally defined by acombined outside diameter or gage diameter determined at least in partby respective gage portions 166 of blades 164. Cutting elements 178 mayinclude a respective cutting surface or cutting face oriented to engageadjacent portions of a downhole formation during rotation of fixedcutter drill bit 160. Hardfacing 126 may be applied on exterior portionsof blades 164 and/or exterior portions of bit body 162. For example,respective hardfacing 126 may be disposed on gage portion 166 of eachblade 164.

Turning now to FIG. 4, a hardfacing system 200 is illustrated. As shown,hardfacing system 200 may represent various hardfacing systems describedherein. Hardfacing system 200 may include an application device 202, afirst processor 204, which controls temperature, a second processor 206,which controls motion, a first positioner 208 coupled to applicationdevice 202, and a second positioner 210. Hardfacing system 200 may be amotion controlled system that may have multiple axes of motion includinga first axis in an X direction, a second axis in a Y direction, a thirdaxis in a Z direction, a fourth axis in a first 360 degree (360°)rotational direction, and a fifth axis in a second 360° rotationaldirection, where the fourth and fifth axis allow three dimensionalspherical motion. Application device 202 includes a container forholding molten hardfacing and an applicator for allowing the moltenhardfacing to flow out of application device 202 and onto a downholetool. Application device 202 may also include a hardfacing heat sourcethat heats the hardfacing. For example, application device 202 mayinclude an extruder 212 having a crucible 216 coupled to a nozzle 218,an induction coil 220, which is a hardfacing heat source, surroundingcrucible 216 to heat hardfacing in crucible 216, and a downhole toolheat source 214 to provide heat to a portion of a drill bit, such as aportion of respective roller cone assembly 122 of drill bit 120.

Crucible 216 may be a container made of a non-metallic material that maybe capable of being heated to at least a crucible threshold temperature.The non-metallic material may be a ceramic material, or a graphite-basedcomposite material. Crucible 216 may have a top having a top openingthat may allow hardfacing, such as non-melted hardfacing, to be fed intocrucible and a bottom having a bottom opening that may allow meltedhardfacing to flow into nozzle 218 coupled to the bottom of crucible216. “Melted hardfacing” is hardfacing in which the matrix material ismelted, but the hard material particles are not melted, allowing thehardfacing to flow. The crucible threshold temperature may be between3,500° F. and 4,000° F. Hardfacing matrix material melting points aretypically between 1,000° F. and 4,000° F.

Nozzle 218 may be capable of being heated to at least the cruciblethreshold temperature of crucible 216. Nozzle 218 may be made of anon-metallic material, such as a non-metallic material suitable forcrucible 216. It may be made of the same material as crucible 216.Nozzle 218 may have a funnel shape, a large opening at the large end ofthe funnel shape, and a small opening at the small end of the funnelshape. Crucible 216 may be coupled to the large end of nozzle 218.Extruder 212 may be substantially vertical within application device 202with the small opening of nozzle 218 positioned in a downward position.The size of the small opening of nozzle 218 may allow particles inmelted hardfacing to pass through the small opening of nozzle 218 andmay also allow a rate of flow of the melted hardfacing flowing throughnozzle 218 to be controlled. The size of the small opening of nozzle 218may be based on the size of the hard material particles in the meltedhardfacing. For example, the size of the small opening of nozzle 218 maybe larger when larger sized hard material particles, such as tungstencarbide pellets, are included in the hardfacing and may be smaller whensmaller hard material particles, such as tungsten carbide powders, areincluded in the hardfacing.

Induction coil 220 may be a helical wound coil, a solenoid coil, oranother type of coil, which may be made from copper tube, and solidcopper coil brazed together, or other types and configurations ofmaterial. Induction coil 220 may generate heat up to the cruciblethreshold temperature. During operation, induction coil 220 may receivepower from a power supply (not shown) causing an alternating current(A/C) in induction coil 220, which may produce an electromagnetic field.The electromagnetic field may induce an A/C current that may passthrough the hardfacing in crucible 216, which may heat the hardfacing.The power received from the power supply may be controlled such thatinduction coil 220 may provide and maintain the temperature in crucible216 in a first temperate range. The matrix material component of thehardfacing in crucible 216 may melt in the first temperature range, butthe hard material particle component may not. This allows the hardfacingto pool, and flow through nozzle 218. The first temperature range may bebased on the melting point of matrix material of the particular type ofhardfacing. The first temperature range may be 1,000° F. to 4,000° F.The upper limit of the first temperature range may be less than a hardmaterial temperature threshold at which the hard material particles meltand/or experience thermal degradation and/or damage. For example, if thehard material particles are tungsten carbide particles, the hardmaterial temperature threshold may be 3,500° F., or between 3,500° F. to4,000° F.

Downhole tool heat source 214 may have a fixed position with respect tothe components of application device 202 that contain and apply themelted hardfacing, such as crucible 216 or nozzle 218. Downhole toolheat source 214 may be a tungsten inert gas (TIG) torch or other heatsource that produces an arc, and an oxygen acetylene torch or other heatsource that produces a flame, or another heat source. Downhole tool heatsource 214 may be substantially vertical within application device 202to provide heat in a downward direction. Extruder 212 and downhole toolheat source 214 may be positioned relative to each other withinapplication device 202 to allow downhole tool heat source 214 to precedeextruder 212 during hardfacing application to prevent downhole tool heatsource 214 from raising the temperature of the melted hardfacing.Extruder 212 and downhole tool heat source 214 may be positioned at adistance in a second distance range from each other. The second distancerange may be between 1 cm to 1 m. During operation, downhole tool heatsource 214 may maintain a temperature in a second temperature range. Thesecond temperature range may be between 11,000° F. to 35,000° F. and maybe based, in part, on a first duration of time needed to melt a portionof the surface of the drill bit, particularly a base metal in theportion of the surface, when downhole tool heat source 214 has atemperature in the second temperature range. The portion of the surface,particularly a base metal therein, typically melts a temperature belowthe second temperature range. For instance, the portion of the surfacemay melt at a temperature of 2,500° F. to 2,600° F. The secondtemperature range is higher than the temperature needed to melt theportion of the surface because downhole tool heat source 214 typicallydoes not remain at a distance in a first distance range from the portionof the surface for a duration of time sufficient to raise the surface tothe second temperature range; downhole tool heat source 214 typicallyremains at the distance in the first distance range from the portion ofthe surface for an amount of time sufficient to melt the portion of thesurface and potentially for a short duration longer, for instance toensure the melting has occurred. The first distance range may be between¼ cm to 20 cm. Downhole tool heat source 214 may cause the portion ofthe surface of the drill bit to melt in less than one second and mayeven cause melting almost instantaneously, such as when a TIG torch isused as downhole tool heat source 214.

The second temperature range is typically higher than the melting pointof the hard material particles in the hardfacing, or at a temperaturewhich causes thermal degradation and/or damage to the hard materialparticles, such that it is advantageous to protect the hard materialparticles from reaching temperatures in the second temperature range. Asa result, the first temperature range provided by induction coil 220 maybe less than the second temperature range provided by downhole tool heatsource 214.

First positioner 208 may include a motion controlled platform, a roboticarm, a Cartesian coordinate robotic arm, a cylindrical coordinaterobotic arm, a spherical coordinate robot arm, an articulated robot arm,motors, arms, or another type of robot arm.

First positioner 208 may be able to move application device 202 back andforth along the first axis in the X direction, side to side along thesecond axis in the Y direction, and up and down along the third axis inthe Z direction.

Second positioner 210 may include a motion controlled platform, arobotic arm, a Cartesian coordinate robotic arm, a cylindricalcoordinate robotic arm, a spherical coordinate robot arm, an articulatedrobot arm, motors, arms, or another type of robot arm.

Second positioner 210 may be able to move a portion of a drill bit, suchas a respective roller cone assembly 122 of drill bit 120, back andforth along the first axis in the X direction, side to side along thesecond axis in the Y direction, up and down along the third axis in theZ direction, rotate the portion of the drill bit along a fourth axis ina first 360° rotational direction, and rotate the portion of the drillbit along a fifth axis in a second 360° rotational direction.

Second positioner 210 may be able to couple to the portion of the drillbit whose surface is hardfaced, by second positioner 210 grasping andholding the portion of the drill bit, or mounting the portion of thedrill bit to second positioner 210, or by another type of couplingtechnique. The portion of the drill bit may have a plurality ofsurfaces. Second positioner 210 may be able to move and rotate theportion of the drill bit to move a particular surface of the pluralityof surfaces of the portion of the drill bit beneath extruder 212 suchthat extruder 212 may apply melted hardfacing on the particular surface.

First processor 204 may be a microprocessor, a microcontroller unitwhich may be a small computer or a single integrated circuit, a systemon a chip (SoC) device, or another type of processor. First processor204 may include one or more central processing units (CPUs), one or moreprocessor cores, memory, an input/output (I/O) module, one or more I/Odevices, and program memory. Memory and program memory may store one ormore programs including a temperature control program, which may includeinstructions executable by first processor 204. Such instructions mayinclude receiving data regarding the temperature of a heat source,comparing the data to a temperature range, and, if the temperature isnot within the temperature range, sending a signal to the heat source toincrease or decrease the temperature.

During operation, first processor 204 may control the heat supplied bythe hardfacing heat source. For example first processor 204 may executethe temperature control program to control and maintain power suppliedby a power supply that may cause an A/C current in induction coil 220,previously described. By first processor 204 controlling and maintainingthe power and A/C current in induction coil 220, first processor 204 maycontrol and maintain the first temperature range provided by inductioncoil 220, which may cause the matrix material component of thehardfacing in crucible 216 to melt. First processor 204 may also controlthe second temperature range provided by downhole tool heat source 214,which may melt a particular portion of the surface of the drill bitbeneath downhole tool heat source 214.

Second processor 206 may be a microprocessor, a microcontroller unitwhich may be a small computer or a single integrated circuit, a systemon a chip (SoC) device, or another type of processor. Second processor206 may include one or more central processing units (CPUs), one or moreprocessor cores, memory, an input/output (I/O) module, one or more I/Odevices, and program memory. Memory and program memory may store one ormore programs including a motion control program, which may includeinstructions executable by second processor 204. Such instructions mayinclude receiving data regarding the position of the application device,position of the downhole tool, the relative positions of the applicationdevice and the downhole tool, the position of the first positioner, theposition of the second positioner, or any combinations thereof,comparing the data to one or more pre-selected positions, and, if thedata and the pre-selected position do not match, optionally within aspecified tolerance, sending a signal to the second processor to movethe application device, the downhole tool, the first positioner, thesecond positions, or any combinations thereof.

-   Second processor 206 and first processor 204 may be the same    processor.

During operation, second processor 206 may execute the motion controlprogram to control the movement of first positioner 208 back and forthalong the first axis in the X direction, side to side along the secondaxis in the second direction, and up and down along the third axis inthe Z direction that may position downhole tool heat source 214 and theportion of application device 202 that applies melted hardfacing, suchas nozzle 218, over a portion of the drill bit that may allow downholetool heat source 214 to heat a particular surface of a plurality ofsurfaces of the portion of the drill bit and application device 202 tosubsequently apply melted hardfacing on the particular surface of theplurality of surfaces of the portion of the drill bit. Second processor206 may also control the movement of second positioner 210 back andforth along the first axis in the X direction, side to side along thesecond axis in the Y direction, up and down along the third axis in theZ direction, in a first 360° rotational direction along the fourth axis,and in a second 360° rotational direction along the fifth axis which mayallow second positioner 210 to position the particular surface of theplurality of surfaces of the portion of the drill bit beneath heatsource 214 and nozzle 218 to allow heat source 214 to melt the basemetal of the particular surface and allow nozzle 218 to subsequentlyapply melted hardfacing on the particular surface. When second processor206 is not controlling the movement of second positioner 210, secondprocessor 206 may also position downhole heat source 214 and nozzle 218over the particular surface of the plurality of surfaces of the portionof the drill bit to allow downhole tool heat source 214 to melt the basemetal of the particular surface and allow nozzle 218 to subsequentlyapply melted hardfacing on the particular surface. Second processor 206may coordinate the control of the movement of first positioner 208 andthe movement of second positioner 210 to apply melted hardfacing on theparticular surface and allow the melted base metal of the particularsurface to bond with the applied melted hardfacing. Second processor 206may control the movement of second positioner 210 to position othersurfaces of the portion of the drill beneath nozzle 218 and heat source214 for application of melted hardfacing on the melted base metal of theother surfaces as previously described. The operation of hardfacingsystem 200 is described in further detail below.

Turning now to FIG. 5, hardfacing system 200, while applying hardfacingon selected surfaces of a drill bit is illustrated. FIG. 5 illustrateshardfacing system 200 used on exemplary roller cone assembly 122.Hardfacing system 200 may hardface other portions of drill bits anddownhole tools.

Second processor 206 controls first positioner 208 to position nozzle218 and downhole tool heat source 214 over roller cone assembly 122.Second processor 206 may also control second positioner 210 to positionthe particular surface of the plurality of surfaces of roller coneassembly 122 beneath nozzle 218 and downhole tool heat source 214. Whensecond processor 206 is not controlling second positioner 210, secondprocessor 206 may also control first positioner 208 to position nozzle218 and downhole tool heat source 214 over a particular surface of aplurality of surfaces of roller cone assembly 122 when movement ofsecond positioner 210. Second processor 206 may include sensors (notshown) that may allow second processor 206 to control the positions ofnozzle 218 and downhole tool heat source 214 and the position of theparticular surface roller cone assembly 122 relative to each other.

Similar to a 3D printer, hardfacing 302 may be fed into crucible 216through the top of crucible 216 in a downward direction 304. Hardfacing302 may be in the form of a hardfacing rod, a spool of hardfacing, and ahardfacing powder, or another form. First processor 204 may controlinduction coil 220 to maintain its temperature in the first temperaturerange, which may cause the matrix material in hardfacing 302 fed intocrucible 216 to melt and pool while hard material particles ofhardfacing 302 may remain solid. The matrix material, once melted incrucible 216, may be generally maintained at a temperature in the firsttemperature range using induction coil 220.

The first temperature generated by induction coil 220 may be at least ashigh as the melting point of the matrix material in the hardfacing, butless than the crucible threshold temperature. Melted hardfacing 302 incrucible 216 may flow into nozzle 218 in downward direction 304 and beextruded out of the small opening of nozzle 218.

During the extrusion of melted hardfacing 302, depicted as extrudedhardfacing 302, second processor 206 may utilize the sensors of secondprocessor 206 to control the movement of first positioner 208 so thatnozzle 218 moves up and down along the Z-axis in the Z direction tofollow the contour of the particular surface of roller cone assembly122, which may allow the extruded hardfacing 302 to be applied on theparticular surface shown as applied hardfacing 126. When the extrudedhardfacing 504 is applied on a substantially flat surface of roller coneassembly 122, the up and down movement of nozzle 218 may be minimal.When the extruded hardfacing 302 is applied on a substantially concaveor convex surface of roller cone assembly 122, the up and down movementof nozzle 218 may be more pronounced.

Second processor 206 may utilize the sensors of second processor 206 andmay also control the movement of second positioner 210 so that theparticular surface of roller cone assembly 122 may be in a horizontalposition and the particular surface may oscillate back and forth alongthe X-axis in the X direction, side to side along the Y-axis in the Ydirection, up and down along the third axis in the Z direction, rotatealong the fourth axis within the first 360° of rotation, and rotatealong the fifth axis within the second 360° of rotation such that theparticular surface may be beneath nozzle 218 and downhole tool heatsource 214 while nozzle 218 is extruding extruded hardfacing 302 andapplying applied hardfacing on the particular surface. Having theparticular surface of roller cone assembly 122 in a horizontal positionmay simplify the hardfacing and may prevent applied melted hardfacingfrom flowing off the particular surface. Oscillating the particularsurface of roller cone assembly 122 back and forth, side to side, up anddown, and rotating roller cone assembly 122 within the first and second360° of rotation during the complete application process 300 may allowextruded hardfacing 302 to be applied in a layer of applied hardfacing126 over substantially the entire particular surface.

While hardfacing is applied on the particular surface, heat source 214may be at second temperature range and may apply heat to the particularsurface, thereby causing a portion of the particular surface,particularly a base metal therein, at a distance within the distancerange from downhole tool heat source 214 to melt. The portion of theparticular surface at the distance within the distance range fromdownhole tool heat source 214 may melt in less than the first durationof time, as previously described. Melting the particular surface usingheat source 214 may eliminate the need to pre-heat roller cone assembly122 prior to applying hardfacing.

Downhole tool heat source 214 may be positioned and controlled such thathard material particles in the hardfacing do not experience thermaldamage and/or degradation due to exposure to high temperatures providedby downhole tool heat source 214. FIGS. 6A and 6B shows examples of suchthermal damage and/or degradation of tungsten carbide particles inhardfacing. FIG. 6A shows the dissolution and settling damage oftungsten carbide particles in hardfacing that may result when thehardfacing is exposed to a TIG torch. The temperature of the TIG torchmay be as high as 11,000° F. or even 35,000° F., which is above themelting point of the tungsten carbide and many other hard materials thatmay be used in the hardfacing. FIG. 6B shows thermal damage and/ordegradation of tungsten carbide particles that may result when thehardfacing is exposed to an oxygen-acetylene torch. The excessive heatmay cause a halo effect 400 in the tungsten carbide particles.

The placement of nozzle 218 and downhole tool heat source 214 ofhardfacing system 200 of FIGS. 4 and 5 relative to each other mayprevent or minimize these types of damage and/or degradation of hardmaterial particles, such as tungsten carbide particles. First processor204 also prevents and minimizes damage and/or degradation of hardmaterial particles, such as tungsten carbide particles, by controllingand maintaining the temperature of induction coil 220 to keep the hardmaterial particles from experiencing a temperature above the hardmaterial temperature threshold.

FIG. 7 is a flow chart of a method 500 for 3D printing hardfacing, asdescribed herein. Method 500 may be performed using hardfacing system200 (such as depicted in FIGS. 4 and 5) and, in particular, byapplication device 202, first processor 204, second processor 206, firstpositioner 208, and second positioner 210. Other hardfacing systems mayalso be used. Certain operations described in method 500 may be optionalor may be rearranged in variant methods.

In step 502, a first processor of a hardfacing system causes ahardfacing heat source, such as an induction coil surrounding a crucibleof an extruder of an application device, to generate a first temperaturein a container holding hardfacing, such as the crucible. The firsttemperature is in a first temperature range at which a matrix materialcomponent of the hardfacing melts to form melted hardfacing, while hardmaterial particles in the hardfacing remain unmelted.

In step 504, which may occur prior to, after, or simultaneously withstep 502, a second processor of the hardfacing system controls movementof a first positioner and a second positioner of the hardfacing systemto place the hardfacing system in a position that allows a surface ofthe drill bit to be hardfaced. The first positioner moves theapplication device along a first set of one or more axes of motion andthe second positioner moves a drill bit along a second set of one ormore axes of motion. The surface of the drill bit to be hardfaced has aplurality of portions.

In step 506, a downhole tool heat source is positioned at a firstdistance from one portion of the surface of the drill bit for a setperiod of time. A first processor controls the downhole tool heat sourcepositioned at the first distance from the portion of a surface of thedrill bit such that the downhole tool heat source is at a secondtemperature in a second temperature range. The portion of the surface,or a component thereof such as a base metal, melts within a set periodof time when positioned at the first distance in a first distance rangefrom the downhole tool heat source at the second temperature to form amelted portion of the surface.

In step 508, the downhole tool heat source is moved from its position atthe first distance from the melted portion of the surface of the drillbit to a position at the first distance from another portion of thesurface of the drill bit.

In step 510, which may be simultaneous with step 508, the first and/orsecond positioner(s) position(s) the crucible over the melted portion ofthe surface of the drill bit and melted hardfacing flows through theapplications device, such as through a nozzle coupled to the crucible,and onto the melted portion of the surface of the drill bit, which has atemperature less than a hard material threshold temperature of hardmaterial particles in the hardfacing.

In step 512, the melted hardfacing bonds or alloys with the meltedportion of the surface, such as melted base metal.

In step 514, if the surface is not completely hardfaced, then theprocess returns to step 506. If the surface is completely hardfaced,then the process ends.

As disclosed herein, systems and methods for 3D printing hardfacing ondownhole tools using a hardfacing system. The present disclosure alsoprovides generating a first temperature in an application device of thehardfacing system to cause hardfacing in the application device to meltand flow through the application device without melting particles in thehardfacing. The present disclosure further provides a downhole tool heatsource positioned at a distance from a first surface of a downhole toolsuch that the heat source is at a second temperature that melts thefirst surface. The present disclosure also provides applying the meltedhardfacing from the application device such that the melted firstsurface and the melted hardfacing bond.

In an embodiment A, the present disclosure provides a hardfacing system.The hardfacing system includes an application device including ahardfacing heat source and a downhole tool heat source. The hardfacingsystem also includes a first processor that controls the hardfacing heatsource to maintain a first temperature to cause a matrix material inhardfacing in the application device to melt without melting hardmaterial particles in the hardfacing. The hardfacing system furtherincludes a second processor that controls movement of the applicationdevice to place the downhole tool heat source at a first distance from aportion of the surface of the downhole tool for a time sufficient toform a melted portion of the surface.

In an embodiment B, the present disclosure provides a hardfacing system.The hardfacing system includes an application device including ahardfacing heat source and a downhole tool heat source. The hardfacingsystem also includes a first processor that controls the hardfacing heatsource to maintain a first temperature to cause a matrix material inhardfacing in the application device to melt without melting hardmaterial particles in the hardfacing, to form melted hardfacing thatflows through the application device and controls the downhole tool heatsource to maintain a second temperature to cause the downhole tool heatsource to melt at least a component of a portion of a surface of adownhole tool positioned at a first distance from the downhole tool heatsource to form a melted portion. The hardfacing system further includesa second processor that controls movement of the application device toplace the downhole tool heat source at the first distance from a portionof the surface of the downhole tool for a time sufficient to form amelted portion of the surface, move the downhole tool heat source awayfrom the melted portion of the surface, and move the application deviceso that the melted hardfacing flows onto the melted portion of thesurface of the downhole tool and the melted hardfacing bonds or alloyswith the melted portion of the surface.

In an embodiment C, the present disclosure provides a hardfacing system.The hardfacing system includes an application device including ahardfacing heat source and a downhole tool heat source. The hardfacingsystem also includes a first processor that controls the hardfacing heatsource to maintain a first temperature to cause a matrix material inhardfacing in the application device to melt without melting hardmaterial particles in the hardfacing, to form melted hardfacing thatflows through the application device and controls the downhole tool heatsource to maintain a second temperature to cause the downhole tool heatsource to melt at least a component of a portion of a surface of adownhole tool positioned at a first distance from the downhole tool heatsource to form a melted portion. The hardfacing system further includesa second processor that controls movement of the application device toplace the downhole tool heat source at the first distance from a portionof the surface of the downhole tool for a time sufficient to form amelted portion of the surface, move the downhole tool heat source awayfrom the melted portion of the surface, and move the application deviceso that the melted hardfacing flows onto the melted portion of thesurface of the downhole tool and the melted hardfacing bonds or alloyswith the melted portion of the surface.

In an embodiment D, the present disclosure provides a method ofhardfacing a downhole tool. The method includes melting, in anapplication device, a matrix material in hardfacing at a firsttemperature without melting hard material particles in the hardfacing toform melted hardfacing, positioning a downhole tool heat source of theapplication device at a second temperature at a first distance from aportion of a surface of a downhole tool to form a melted portion of thesurface, moving the downhole tool heat source away from the meltedportion of the surface, and positioning the application device over themelted portion of the surface so that the melted hardfacing flows out ofthe application device and onto the melted portion of the surface tobond or alloy with the melted portion of the surface.

In further embodiments, the system of embodiment A may be used toimplement the method of embodiment D, the system of embodiment B may beused to implement the method of embodiment D, the system of embodiment Cmay be used to implement the method of embodiment D, the method ofembodiment D may be implemented using the system of embodiment A, themethod of embodiment D may be implemented using the system of embodimentB, the method of embodiment D may be implemented using the system ofembodiment C, in addition, the system or method may have any one orcombinations of the following additional features, unless such featuresare clearly mutually exclusive: i) the first and second processor may bethe same processor; ii) the surface of the downhole tool may include aplurality of portions and the second processor may further controlmovement of the application device to allow melted hardfacing to bond oralloy with at least two of the plurality of portions; iii) the surfaceof the downhole tool may include a plurality of portions and the secondprocessor may further control movement of the application device toallow melted hardfacing to bond or alloy with substantially all of theplurality of portions; iv) the application device may further include anextruder having a crucible coupled to a nozzle, in which the hardfacingheat source is an induction coil surrounding the crucible, thehardfacing is in the crucible and the melted hardfacing flows throughthe nozzle, and the extruder and the downhole tool heat source arepositioned relative to each other within the application device suchthat the downhole tool heat source is positioned at the first distancefrom the portion of the surface before the crucible is positioned overthat portion as the second processor positions the application device;v) the extruder and the downhole tool heat source may have fixedpositions relative to one another within the application device; vi) thefirst temperature may be within a first temperature range; vii) thesecond temperature may be within a second temperature range, and whereinthe first temperature range may be less than the second temperaturerange; viii) the first temperature range may be between 1,000° F. and4,000° F. and the second temperature range may be between 11,000° F. and35,000° F.; ix) the first distance may be within a first distance range;x) the first distance range may be between ¼ cm and 20 cm; xi) the hardmaterial particles may have a melting point and the first temperaturerange may be less than the melting point of the hard material particlesin the hardfacing; xii) the second processor may control the movement ofthe application device in an X-axis of motion, a Y-axis of motion, and aZ-axis of motion, in which the X-axis of motion, Y-axis of motion, andZ-axis of motion are defined by 90 degree angles with respect to oneanother, and the second processor may further control movement of thedownhole tool in the X-axis of motion, the Y-axis of motion, the Z-axisof motion, on a fourth axis with a first 360 degree rotationaldirection, and on a fifth axis with a second 360 degree rotationaldirection; xiii) the second processor may control the movement of theapplication device at least on the X-axis and the Z-axis; xiv) thesecond processor may further control movement of a first positioner ofthe hardfacing system to control the movement of the application device;xv) the second processor may further control movement of a secondpositioner of the hardfacing system to control the movement of thedownhole tool at least on the X-axis, the Y-axis, the fourth axis, andthe fifth axis; xvi) the second processor may further control movementof a second positioner of the hardfacing system to further controlmovement of the downhole tool; xvii) the first positioner may include amotion controlled platform, a robotic arm, a Cartesian coordinaterobotic arm, a cylindrical coordinate robotic arm, a sphericalcoordinate robot arm, and/or an articulated robot arm; xviii) the secondpositioner may include a motion controlled platform, a robotic arm, aCartesian coordinate robotic arm, a cylindrical coordinate robotic arm,a spherical coordinate robot arm, and/or an articulated robot arm; xix)the hardfacing may include a hardfacing rod, a hardfacing spool, and ahardfacing powder; xx) the downhole tool heat source may include atungsten inert gas torch or an oxygen acetylene torch; xxi) the methodmay include bonding or alloying melted hardfacing with at least two of aplurality of portions of the surface; xxii) the method may includebonding or alloying melted hardfacing with substantially all of aplurality of portions of the surface; xxiii) at least one positioning ormoving step may include moving the downhole tool at least on an X-axisof motion, a Y-axis of motion, a Z-axis of motion, a fourth axis ofmotion, and a fifth axis of motion; xxiv) positioning the applicationdevice over the melted portion may include moving the application deviceat least on the X-axis of motion, the Y-axis of motion, and a Z-axis ofmotion; xxv) the X-axis of motion, the Y-axis of motion, and the Z-axisof motion may be by 90 degree angles with respect to one another, andthe fourth axis of motion may be defined by a first 360 degreerotational direction, and the fifth axis of motion may be defined by asecond 360 degree rotational direction; xxvi) the downhole tool may be arotary drill bit, a roller cone drill bit, a fixed-cutter drill bit, areamer, a core bit, an under reamer, a near bit reamer, a hole opener, astabilizer, a centralizer, or a shock absorber assembly; xxvii) thehardfacing may include a hardfacing rod, a hardfacing spool, or ahardfacing powder; xxviii) the hard material particles in the hardfacingmay include a powder or pellets; xxix) the matrix material may includeat least one material selected from the group consisting of a metal, ametal alloy, a ceramic alloy, and a cermet; xxx) the matrix material mayinclude at least one material selected from the group consisting of aniron alloy, an iron, manganese, and silicon alloy, copper, a copperalloy, nickel, a nickel alloy, cobalt, and a cobalt alloy; xxxi) thehard material particles may include at least one of a metal boride, ametal carbide, a metal nitride, and a metal silicide; xxxii) the hardmaterial particles may include at least one material selected from thegroup consisting of tungsten, tungsten boride tungsten carbide, tungstennitride, tungsten oxide, tungsten silicide, copper, copper boride,copper carbide, copper oxide, copper nitride, copper silicide, niobium,niobium boride niobium carbide, niobium nitride, niobium oxide, niobiumsilicide, vanadium, vanadium boride vanadium carbide, vanadium nitride,vanadium oxide, vanadium silicide, molybdenum, molybdenum boridemolybdenum carbide, molybdenum oxide, molybdenum nitride, molybdenumsilicide, titanium, titanium boride titanium carbide, titanium oxide,titanium nitride, titanium silicide, tantalum, tantalum boride tantalumcarbide, tantalum oxide, tantalum nitride, tantalum silicide, zirconium,zirconium boride, zirconium carbide, zirconium oxide, zirconium nitride,zirconium silicide, chromium, chromium boride chromium carbide, chromiumoxide, chromium nitride, chromium silicide, yttrium, yttrium borideyttrium carbide, yttrium oxide, yttrium nitride, yttrium silicide,boron, boron carbide, boron oxide, boron nitride, boron silicide,silicon, silicon boride, silicon carbide, silicon oxide, and siliconnitride; xxxiii) the method may include not heating the downhole toolother than with the downhole tool heat source.

The present disclosure further includes downhole tools, such as drillbits, hardfaced using any of the above systems or methods as well asmethods of forming a wellbore using such downhole tools.

The above disclosed subject matter is to be considered illustrative, andnot restrictive, and the appended claims are intended to cover all suchmodifications, enhancements, and other embodiments which fall within thetrue spirit and scope of the present disclosure. Thus, to the maximumextent allowed by law, the scope of the present disclosure is to bedetermined by the broadest permissible interpretation of the followingclaims and their equivalents, and shall not be restricted or limited bythe foregoing detailed description.

The invention claimed is:
 1. A method comprising: melting, in anapplication device, a matrix material in hardfacing at a firsttemperature without melting hard material particles in the hardfacing toform melted hardfacing; positioning a downhole tool heat source of theapplication device at a second temperature at a first distance from aportion of a surface of a downhole tool to form a melted portion of thesurface; executing a motion control program to calculate a movement ofthe application device; moving, based on the calculation, the downholetool heat source away from the melted portion of the surface; andpositioning, based on the calculation, the application device over themelted portion of the surface so that the melted hardfacing flows out ofthe application device and onto the melted portion of the surface tobond or alloy with the melted portion of the surface.
 2. The method ofclaim 1, further comprising bonding or alloying melted hardfacing withat least two of a plurality of portions of the surface.
 3. The method ofclaim 1, further comprising bonding or alloying melted hardfacing withsubstantially all of a plurality of portions of the surface.
 4. Themethod of claim 1, wherein the first temperature is within a firsttemperature range.
 5. The method of claim 4, wherein the secondtemperature is within a second temperature range and the firsttemperature range is less than the second temperature range.
 6. Themethod of claim 5, wherein the first temperature range is between 1,000°F. and 4,000° F. and the second temperature range is between 11,000° F.and 35,000° F.
 7. The method of claim 1, wherein the first distance iswithin a first distance range.
 8. The method of claim 7, wherein thefirst distance range is between ¼ cm and 20 cm.
 9. The method of claim6, wherein the hard material particles have a melting point and thefirst temperature range is less than the melting point of the hardmaterial particles in the hardfacing.
 10. The method of claim 1, whereinthe moving step comprises moving the downhole tool along at least one ofan X-axis of motion, a Y-axis of motion, a Z-axis of motion, a fourthaxis of motion, and a fifth axis of motion.
 11. The method of claim 1,wherein positioning the application device over the melted portioncomprises moving the application device along at least one of a X-axisof motion, a Y-axis of motion, and a Z-axis of motion.
 12. The method ofclaim 10, wherein the X-axis of motion, the Y-axis of motion, and theZ-axis of motion are defined by 90 degree angles with respect to oneanother, and wherein the fourth axis of motion is defined by a first 360degree rotational direction, and the fifth axis of motion is defined bya second 360 degree rotational direction.
 13. The method of claim 1,wherein the downhole tool is a rotary drill bit, a roller cone drillbit, a fixed-cutter drill bit, a reamer, a core bit, an under reamer, anear bit reamer, a hole opener, a stabilizer, a centralizer, or a shockabsorber assembly.
 14. The method of claim 1, wherein the hardfacingcomprises a hardfacing rod, a hardfacing spool, or a hardfacing powder.15. The method of claim 1, wherein the hard material particles in thehardfacing comprise a powder or pellets.
 16. The method of claim 1,wherein the matrix material comprises at least one material selectedfrom the group consisting of a metal, a metal alloy, a ceramic alloy,and a cermet.
 17. The method of claim 1, wherein the matrix materialcomprises at least one material selected from the group consisting of aniron alloy, an iron, manganese, and silicon alloy, copper, a copperalloy, nickel, a nickel alloy, cobalt, and a cobalt alloy.
 18. Themethod of claim 1, wherein the hard material particles comprise at leastone of a metal boride, a metal carbide, a metal nitride, and a metalsilicide.
 19. The method of claim 1, wherein the hard material particlescomprise at least one material selected from the group consisting oftungsten, tungsten boride tungsten carbide, tungsten nitride, tungstenoxide, tungsten silicide, copper, copper boride, copper carbide, copperoxide, copper nitride, copper silicide, niobium, niobium boride niobiumcarbide, niobium nitride, niobium oxide, niobium silicide, vanadium,vanadium boride vanadium carbide, vanadium nitride, vanadium oxide,vanadium silicide, molybdenum, molybdenum boride molybdenum carbide,molybdenum oxide, molybdenum nitride, molybdenum silicide, titanium,titanium boride titanium carbide, titanium oxide, titanium nitride,titanium silicide, tantalum, tantalum boride tantalum carbide, tantalumoxide, tantalum nitride, tantalum silicide, zirconium, zirconium boride,zirconium carbide, zirconium oxide, zirconium nitride, zirconiumsilicide, chromium, chromium boride chromium carbide, chromium oxide,chromium nitride, chromium silicide, yttrium, yttrium boride yttriumcarbide, yttrium oxide, yttrium nitride, yttrium silicide, boron, boroncarbide, boron oxide, boron nitride, boron silicide, silicon, siliconboride, silicon carbide, silicon oxide, and silicon nitride.
 20. Themethod of claim 1, further comprising not heating the downhole toolother than with the downhole tool heat source.